diff --git a/gcc/builtins.cc b/gcc/builtins.cc
index e6816d5c865..35b9197945f 100644
--- a/gcc/builtins.cc
+++ b/gcc/builtins.cc
@@ -6029,8 +6029,8 @@ expand_ifn_atomic_compare_exchange_into_call (gcall *call, machine_mode mode)
       if (GET_MODE (boolret) != mode)
 	boolret = convert_modes (mode, GET_MODE (boolret), boolret, 1);
       x = force_reg (mode, x);
-      write_complex_part (target, boolret, true);
-      write_complex_part (target, x, false);
+      write_complex_part (target, boolret, true, true);
+      write_complex_part (target, x, false, false);
     }
 }
 
@@ -6085,8 +6085,8 @@ expand_ifn_atomic_compare_exchange (gcall *call)
       rtx target = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
       if (GET_MODE (boolret) != mode)
 	boolret = convert_modes (mode, GET_MODE (boolret), boolret, 1);
-      write_complex_part (target, boolret, true);
-      write_complex_part (target, oldval, false);
+      write_complex_part (target, boolret, true, true);
+      write_complex_part (target, oldval, false, false);
     }
 }
 
diff --git a/gcc/calls.cc b/gcc/calls.cc
index 7f3cf5fd047..bc96aff38f0 100644
--- a/gcc/calls.cc
+++ b/gcc/calls.cc
@@ -1226,7 +1226,7 @@ store_unaligned_arguments_into_pseudos (struct arg_data *args, int num_actuals)
 
 	    bytes -= bitsize / BITS_PER_UNIT;
 	    store_bit_field (reg, bitsize, endian_correction, 0, 0,
-			     word_mode, word, false);
+			     word_mode, word, false, false);
 	  }
       }
 }
diff --git a/gcc/emit-rtl.cc b/gcc/emit-rtl.cc
index 1e02ae254d0..3929ee08986 100644
--- a/gcc/emit-rtl.cc
+++ b/gcc/emit-rtl.cc
@@ -947,9 +947,11 @@ validate_subreg (machine_mode omode, machine_mode imode,
 	   && GET_MODE_INNER (omode) == GET_MODE_INNER (imode))
     ;
   /* Subregs involving floating point modes are not allowed to
-     change size.  Therefore (subreg:DI (reg:DF) 0) is fine, but
+     change size unless it's an insert into a complex mode.
+     Therefore (subreg:DI (reg:DF) 0) and (subreg:CS (reg:SF) 0) are fine, but
      (subreg:SI (reg:DF) 0) isn't.  */
-  else if (FLOAT_MODE_P (imode) || FLOAT_MODE_P (omode))
+  else if ((FLOAT_MODE_P (imode) || FLOAT_MODE_P (omode))
+	   && !COMPLEX_MODE_P (omode))
     {
       if (! (known_eq (isize, osize)
 	     /* LRA can use subreg to store a floating point value in
diff --git a/gcc/expmed.cc b/gcc/expmed.cc
index c3e4aa8019a..9b01b5a51e7 100644
--- a/gcc/expmed.cc
+++ b/gcc/expmed.cc
@@ -738,13 +738,16 @@ store_bit_field_using_insv (const extraction_insn *insv, rtx op0,
 
    If FALLBACK_P is true, fall back to store_fixed_bit_field if we have
    no other way of implementing the operation.  If FALLBACK_P is false,
-   return false instead.  */
+   return false instead.
+
+   if UNDEFINED_P is true then STR_RTX is undefined and may be set using
+   a subreg instead.  */
 
 static bool
 store_bit_field_1 (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
 		   poly_uint64 bitregion_start, poly_uint64 bitregion_end,
 		   machine_mode fieldmode,
-		   rtx value, bool reverse, bool fallback_p)
+		   rtx value, bool reverse, bool fallback_p, bool undefined_p)
 {
   rtx op0 = str_rtx;
 
@@ -805,8 +808,9 @@ store_bit_field_1 (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
 	      return true;
 	    }
 	}
-      else if (constant_multiple_p (bitnum, regsize * BITS_PER_UNIT, &regnum)
-	       && multiple_p (bitsize, regsize * BITS_PER_UNIT)
+      else if (((constant_multiple_p (bitnum, regsize * BITS_PER_UNIT, &regnum)
+		 && multiple_p (bitsize, regsize * BITS_PER_UNIT))
+		|| undefined_p)
 	       && known_ge (GET_MODE_BITSIZE (GET_MODE (op0)), bitsize))
 	{
 	  sub = simplify_gen_subreg (fieldmode, op0, GET_MODE (op0),
@@ -869,7 +873,7 @@ store_bit_field_1 (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
 					GET_MODE_SIZE (GET_MODE (op0)));
 	  emit_move_insn (temp, op0);
 	  store_bit_field_1 (temp, bitsize, bitnum, 0, 0, fieldmode, value,
-			     reverse, fallback_p);
+			     reverse, fallback_p, undefined_p);
 	  emit_move_insn (op0, temp);
 	  return true;
 	}
@@ -994,7 +998,7 @@ store_integral_bit_field (rtx op0, opt_scalar_int_mode op0_mode,
 				  bitnum + bit_offset,
 				  bitregion_start, bitregion_end,
 				  word_mode,
-				  value_word, reverse, fallback_p))
+				  value_word, reverse, fallback_p, false))
 	    {
 	      delete_insns_since (last);
 	      return false;
@@ -1084,7 +1088,7 @@ store_integral_bit_field (rtx op0, opt_scalar_int_mode op0_mode,
 	  rtx tempreg = copy_to_reg (xop0);
 	  if (store_bit_field_1 (tempreg, bitsize, bitpos,
 				 bitregion_start, bitregion_end,
-				 fieldmode, orig_value, reverse, false))
+				 fieldmode, orig_value, reverse, false, false))
 	    {
 	      emit_move_insn (xop0, tempreg);
 	      return true;
@@ -1112,13 +1116,15 @@ store_integral_bit_field (rtx op0, opt_scalar_int_mode op0_mode,
 
    FIELDMODE is the machine-mode of the FIELD_DECL node for this field.
 
-   If REVERSE is true, the store is to be done in reverse order.  */
+   If REVERSE is true, the store is to be done in reverse order.
+
+   If UNDEFINED_P is true then STR_RTX is currently undefined.  */
 
 void
 store_bit_field (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
 		 poly_uint64 bitregion_start, poly_uint64 bitregion_end,
 		 machine_mode fieldmode,
-		 rtx value, bool reverse)
+		 rtx value, bool reverse, bool undefined_p)
 {
   /* Handle -fstrict-volatile-bitfields in the cases where it applies.  */
   unsigned HOST_WIDE_INT ibitsize = 0, ibitnum = 0;
@@ -1151,7 +1157,7 @@ store_bit_field (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
 	  gcc_assert (ibitnum + ibitsize <= GET_MODE_BITSIZE (int_mode));
 	  temp = copy_to_reg (str_rtx);
 	  if (!store_bit_field_1 (temp, ibitsize, ibitnum, 0, 0,
-				  int_mode, value, reverse, true))
+				  int_mode, value, reverse, true, undefined_p))
 	    gcc_unreachable ();
 
 	  emit_move_insn (str_rtx, temp);
@@ -1186,7 +1192,7 @@ store_bit_field (rtx str_rtx, poly_uint64 bitsize, poly_uint64 bitnum,
 
   if (!store_bit_field_1 (str_rtx, bitsize, bitnum,
 			  bitregion_start, bitregion_end,
-			  fieldmode, value, reverse, true))
+			  fieldmode, value, reverse, true, undefined_p))
     gcc_unreachable ();
 }
 
diff --git a/gcc/expmed.h b/gcc/expmed.h
index ee1ddc82b60..0b2538c4c6b 100644
--- a/gcc/expmed.h
+++ b/gcc/expmed.h
@@ -715,7 +715,7 @@ extern rtx expand_divmod (int, enum tree_code, machine_mode, rtx, rtx,
 
 extern void store_bit_field (rtx, poly_uint64, poly_uint64,
 			     poly_uint64, poly_uint64,
-			     machine_mode, rtx, bool);
+			     machine_mode, rtx, bool, bool);
 extern rtx extract_bit_field (rtx, poly_uint64, poly_uint64, int, rtx,
 			      machine_mode, machine_mode, bool, rtx *);
 extern rtx extract_low_bits (machine_mode, machine_mode, rtx);
diff --git a/gcc/expr.cc b/gcc/expr.cc
index 62297379ec9..eb280e6cac3 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -2891,7 +2891,7 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED,
 	  store_bit_field (dest,
 			   adj_bytelen * BITS_PER_UNIT, bytepos * BITS_PER_UNIT,
 			   bytepos * BITS_PER_UNIT, ssize * BITS_PER_UNIT - 1,
-			   VOIDmode, tmps[i], false);
+			   VOIDmode, tmps[i], false, false);
 	}
 
       /* Optimize the access just a bit.  */
@@ -2905,7 +2905,7 @@ emit_group_store (rtx orig_dst, rtx src, tree type ATTRIBUTE_UNUSED,
 
       else
 	store_bit_field (dest, bytelen * BITS_PER_UNIT, bytepos * BITS_PER_UNIT,
-			 0, 0, mode, tmps[i], false);
+			 0, 0, mode, tmps[i], false, false);
     }
 
   /* Copy from the pseudo into the (probable) hard reg.  */
@@ -3038,7 +3038,7 @@ copy_blkmode_from_reg (rtx target, rtx srcreg, tree type)
 					  xbitpos % BITS_PER_WORD, 1,
 					  NULL_RTX, copy_mode, copy_mode,
 					  false, NULL),
-		       false);
+		       false, false);
     }
 }
 
@@ -3140,7 +3140,7 @@ copy_blkmode_to_reg (machine_mode mode_in, tree src)
 					  bitpos % BITS_PER_WORD, 1,
 					  NULL_RTX, word_mode, word_mode,
 					  false, NULL),
-		       false);
+		       false, false);
     }
 
   if (mode == BLKmode)
@@ -3308,8 +3308,8 @@ clear_storage_hints (rtx object, rtx size, enum block_op_methods method,
 	  zero = CONST0_RTX (GET_MODE_INNER (mode));
 	  if (zero != NULL)
 	    {
-	      write_complex_part (object, zero, 0);
-	      write_complex_part (object, zero, 1);
+	      write_complex_part (object, zero, 0, true);
+	      write_complex_part (object, zero, 1, false);
 	      return NULL;
 	    }
 	}
@@ -3470,10 +3470,11 @@ set_storage_via_setmem (rtx object, rtx size, rtx val, unsigned int align,
 
 
 /* Write to one of the components of the complex value CPLX.  Write VAL to
-   the real part if IMAG_P is false, and the imaginary part if its true.  */
+   the real part if IMAG_P is false, and the imaginary part if its true.
+   If UNDEFINED_P then the value in CPLX is currently undefined.  */
 
 void
-write_complex_part (rtx cplx, rtx val, bool imag_p)
+write_complex_part (rtx cplx, rtx val, bool imag_p, bool undefined_p)
 {
   machine_mode cmode;
   scalar_mode imode;
@@ -3528,7 +3529,7 @@ write_complex_part (rtx cplx, rtx val, bool imag_p)
     }
 
   store_bit_field (cplx, ibitsize, imag_p ? ibitsize : 0, 0, 0, imode, val,
-		   false);
+		   false, undefined_p);
 }
 
 /* Extract one of the components of the complex value CPLX.  Extract the
@@ -3781,8 +3782,8 @@ emit_move_complex_parts (rtx x, rtx y)
       && REG_P (x) && !reg_overlap_mentioned_p (x, y))
     emit_clobber (x);
 
-  write_complex_part (x, read_complex_part (y, false), false);
-  write_complex_part (x, read_complex_part (y, true), true);
+  write_complex_part (x, read_complex_part (y, false), false, true);
+  write_complex_part (x, read_complex_part (y, true), true, false);
 
   return get_last_insn ();
 }
@@ -5441,7 +5442,7 @@ expand_assignment (tree to, tree from, bool nontemporal)
 	}
       else
 	store_bit_field (mem, GET_MODE_BITSIZE (mode), 0, 0, 0, mode, reg,
-			 false);
+			 false, false);
       return;
     }
 
@@ -5663,8 +5664,8 @@ expand_assignment (tree to, tree from, bool nontemporal)
 	    concat_store_slow:;
 	      rtx temp = assign_stack_temp (GET_MODE (to_rtx),
 					    GET_MODE_SIZE (GET_MODE (to_rtx)));
-	      write_complex_part (temp, XEXP (to_rtx, 0), false);
-	      write_complex_part (temp, XEXP (to_rtx, 1), true);
+	      write_complex_part (temp, XEXP (to_rtx, 0), false, true);
+	      write_complex_part (temp, XEXP (to_rtx, 1), true, false);
 	      result = store_field (temp, bitsize, bitpos,
 				    bitregion_start, bitregion_end,
 				    mode1, from, get_alias_set (to),
@@ -6222,7 +6223,8 @@ store_expr (tree exp, rtx target, int call_param_p,
 		store_bit_field (target,
 				 rtx_to_poly_int64 (expr_size (exp))
 				 * BITS_PER_UNIT,
-				 0, 0, 0, GET_MODE (temp), temp, reverse);
+				 0, 0, 0, GET_MODE (temp), temp, reverse,
+				 false);
 	    }
 	  else
 	    convert_move (target, temp, TYPE_UNSIGNED (TREE_TYPE (exp)));
@@ -7631,7 +7633,7 @@ store_field (rtx target, poly_int64 bitsize, poly_int64 bitpos,
       gcc_checking_assert (known_ge (bitpos, 0));
       store_bit_field (target, bitsize, bitpos,
 		       bitregion_start, bitregion_end,
-		       mode, temp, reverse);
+		       mode, temp, reverse, false);
 
       return const0_rtx;
     }
@@ -10120,8 +10122,8 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
 	      complex_expr_swap_order:
 		/* Move the imaginary (op1) and real (op0) parts to their
 		   location.  */
-		write_complex_part (target, op1, true);
-		write_complex_part (target, op0, false);
+		write_complex_part (target, op1, true, true);
+		write_complex_part (target, op0, false, false);
 
 		return target;
 	      }
@@ -10150,8 +10152,8 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
 	  }
 
       /* Move the real (op0) and imaginary (op1) parts to their location.  */
-      write_complex_part (target, op0, false);
-      write_complex_part (target, op1, true);
+      write_complex_part (target, op0, false, true);
+      write_complex_part (target, op1, true, false);
 
       return target;
 
@@ -10390,7 +10392,7 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
 	rtx dst = gen_reg_rtx (mode);
 	emit_move_insn (dst, op0);
 	store_bit_field (dst, bitsize, bitpos, 0, 0,
-			 TYPE_MODE (TREE_TYPE (treeop1)), op1, false);
+			 TYPE_MODE (TREE_TYPE (treeop1)), op1, false, false);
 	return dst;
       }
 
diff --git a/gcc/expr.h b/gcc/expr.h
index b00c068f2fa..08b59b8d869 100644
--- a/gcc/expr.h
+++ b/gcc/expr.h
@@ -262,7 +262,7 @@ extern rtx_insn *emit_move_insn_1 (rtx, rtx);
 extern rtx_insn *emit_move_complex_push (machine_mode, rtx, rtx);
 extern rtx_insn *emit_move_complex_parts (rtx, rtx);
 extern rtx read_complex_part (rtx, bool);
-extern void write_complex_part (rtx, rtx, bool);
+extern void write_complex_part (rtx, rtx, bool, bool);
 extern rtx read_complex_part (rtx, bool);
 extern rtx emit_move_resolve_push (machine_mode, rtx);
 
diff --git a/gcc/ifcvt.cc b/gcc/ifcvt.cc
index 25aff38189e..2e8ab396e26 100644
--- a/gcc/ifcvt.cc
+++ b/gcc/ifcvt.cc
@@ -999,7 +999,8 @@ noce_emit_move_insn (rtx x, rtx y)
 		}
 
 	      gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
-	      store_bit_field (op, size, start, 0, 0, GET_MODE (x), y, false);
+	      store_bit_field (op, size, start, 0, 0, GET_MODE (x), y, false,
+			       false);
 	      return;
 	    }
 
@@ -1056,7 +1057,7 @@ noce_emit_move_insn (rtx x, rtx y)
   outmode = GET_MODE (outer);
   bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
   store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos,
-		   0, 0, outmode, y, false);
+		   0, 0, outmode, y, false, false);
 }
 
 /* Return the CC reg if it is used in COND.  */
diff --git a/gcc/internal-fn.cc b/gcc/internal-fn.cc
index 91588f8bc9f..d666ccccf67 100644
--- a/gcc/internal-fn.cc
+++ b/gcc/internal-fn.cc
@@ -815,9 +815,9 @@ expand_arith_set_overflow (tree lhs, rtx target)
 {
   if (TYPE_PRECISION (TREE_TYPE (TREE_TYPE (lhs))) == 1
       && !TYPE_UNSIGNED (TREE_TYPE (TREE_TYPE (lhs))))
-    write_complex_part (target, constm1_rtx, true);
+    write_complex_part (target, constm1_rtx, true, false);
   else
-    write_complex_part (target, const1_rtx, true);
+    write_complex_part (target, const1_rtx, true, false);
 }
 
 /* Helper for expand_*_overflow.  Store RES into the __real__ part
@@ -872,7 +872,7 @@ expand_arith_overflow_result_store (tree lhs, rtx target,
       expand_arith_set_overflow (lhs, target);
       emit_label (done_label);
     }
-  write_complex_part (target, lres, false);
+  write_complex_part (target, lres, false, false);
 }
 
 /* Helper for expand_*_overflow.  Store RES into TARGET.  */
@@ -917,7 +917,7 @@ expand_addsub_overflow (location_t loc, tree_code code, tree lhs,
     {
       target = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
       if (!is_ubsan)
-	write_complex_part (target, const0_rtx, true);
+	write_complex_part (target, const0_rtx, true, false);
     }
 
   /* We assume both operands and result have the same precision
@@ -1362,7 +1362,7 @@ expand_neg_overflow (location_t loc, tree lhs, tree arg1, bool is_ubsan,
     {
       target = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
       if (!is_ubsan)
-	write_complex_part (target, const0_rtx, true);
+	write_complex_part (target, const0_rtx, true, false);
     }
 
   enum insn_code icode = optab_handler (negv3_optab, mode);
@@ -1487,7 +1487,7 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
     {
       target = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
       if (!is_ubsan)
-	write_complex_part (target, const0_rtx, true);
+	write_complex_part (target, const0_rtx, true, false);
     }
 
   if (is_ubsan)
@@ -2304,7 +2304,7 @@ expand_mul_overflow (location_t loc, tree lhs, tree arg0, tree arg1,
       do_compare_rtx_and_jump (op1, res, NE, true, mode, NULL_RTX, NULL,
 			       all_done_label, profile_probability::very_unlikely ());
       emit_label (set_noovf);
-      write_complex_part (target, const0_rtx, true);
+      write_complex_part (target, const0_rtx, true, false);
       emit_label (all_done_label);
     }
 
@@ -2573,7 +2573,7 @@ expand_arith_overflow (enum tree_code code, gimple *stmt)
 	{
 	  /* The infinity precision result will always fit into result.  */
 	  rtx target = expand_expr (lhs, NULL_RTX, VOIDmode, EXPAND_WRITE);
-	  write_complex_part (target, const0_rtx, true);
+	  write_complex_part (target, const0_rtx, true, false);
 	  scalar_int_mode mode = SCALAR_INT_TYPE_MODE (type);
 	  struct separate_ops ops;
 	  ops.code = code;
diff --git a/gcc/testsuite/g++.target/aarch64/complex-init.C b/gcc/testsuite/g++.target/aarch64/complex-init.C
new file mode 100644
index 00000000000..c3637d89824
--- /dev/null
+++ b/gcc/testsuite/g++.target/aarch64/complex-init.C
@@ -0,0 +1,37 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { check-function-bodies "**" "" "" { target { le } } } } */
+
+/*
+** _Z1fii:
+** ...
+** 	bfi	x0, x1, 32, 32
+** 	ret
+*/
+_Complex int f(int a, int b) {
+    _Complex int t = a + b * 1i;
+    return t;
+}
+
+/*
+** _Z2f2ii:
+** ...
+** 	bfi	x0, x1, 32, 32
+** 	ret
+*/
+_Complex int f2(int a, int b) {
+    _Complex int t = {a, b};
+    return t;
+}
+
+/* 
+** _Z12f_convolutedii:
+** ...
+** 	bfi	x0, x1, 32, 32
+** 	ret
+*/
+_Complex int f_convoluted(int a, int b) {
+    _Complex int t = (_Complex int)a;
+    __imag__ t = b;
+    return t;
+}